Reliable biomolecule delivery methods are indispensable tools for many Life Scientists. Transfection, siRNA evaluation and screening of various cell labeling methods are examples where efficient delivery to the target cell culture is crucial. Successful biomolecule non-viral delivery methods for in vitro purposes have to overcome a series of hindrance and avoid toxic effects on the target cell and still efficiently deliver functional biomolecules of choice within the cell. The first step in the delivery process is for the biomolecule to reach the surfaces of the target cells. The biomolecule should be delivered to the cell independent of media components in the cell culture and reach both adherent cell lines and cells in suspension. Once delivered at the cell surface the biomolecule has to either transverse the cell membrane/cell wall or enter the cell through an endocytosis pathway. Once within the endosome pH is low and both the cytosol and the endosome contain various degrading enzymes. Efficient delivery methods should preferably minimize cellular degrading of the biomolecule in question, whether it constitutes a DNA, RNA, protein or other molecule. To achieve a successful delivery process where the biomolecule enter the cell through endocytosis it is desirable to promote endosomal release into the cytosol of as many biomolecules as possible from each endosomal compartment. Once in the cytosol the biomolecule should preferably be targeted to a special intracellular compartment such as for instance the cell nucleus.
The basic technologies for all non-viral biomolecule delivery methods available today can be divided into two approaches. Physical methods like electroporation, microinjection and gene bombardment which deliver the biomolecule through the cell membrane into the cytosol. The chemical/synthetical methods use the target cell endocytosis. Both technologies have specific features as well as limitations and are well established methods.
The increased number of high throughput preclinical cell based in vitro studies on stem cells, primary cell lines as well as cultured standard laboratory cell lines requires efficient, robust and cost effective biomolecule delivery methods. To meet these needs it is desirable to improve delivery efficiency of chemical and synthetic delivery method. One approach to increase the efficiency is to actively promote endosomal release.